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Join us for a new program at the Chicago Botanic Garden on Saturday, May 9: World Bonsai Day!

Observed on the second Saturday in May, this day was established by the World Bonsai Friendship Federation (WBFF) in 2010 to honor WBFF founder and bonsai master Saburo Kato’s contributions to the world of bonsai, and to bring all bonsai enthusiasts together for a day to promote bonsai and friendship throughout the world.

The late bonsai master Saburo Kato

The oldest son of bonsai master Tomekichi Kato, Saburo Kato followed in his father’s footsteps cultivating bonsai, and at his father’s death, became the third-generation owner of Mansei-en Bonsai Garden in Japan, one of the most famous bonsai nurseries in the world. As an author, teacher, and poet, Kato inspired countless people throughout the world to learn the art of bonsai cultivation. He believed so strongly that bonsai could bring peace throughout the world that he founded the WBFF.

In 2014, the following organizations celebrated World Bonsai Day: National Bonsai & Penjing Museum (at the United States National Arboretum), the North Carolina Arboretum, the Morikami Museum and Japanese Gardens, the Pacific Bonsai Museum, and Rosade Bonsai Studio.

Jack Sustic (left), curator, National Bonsai & Penjing Museum (at the United States National Arboretum), with a volunteer, World Bonsai Day 2014

Join me, curator Chris Baker, and some of our bonsai volunteers in the activities below on World Bonsai Day at the Chicago Botanic Garden. The stages of growing bonsai will be featured with specific examples. Explore the tools, pots, wire, etc., used to practice bonsai, and get information on upcoming bonsai classes.

Program Schedule:

10 a.m. to 12:30 p.m.: Demonstration: Bonsai Tree Styling I will demonstrate how major tree shaping is done, with a tree being formed into a bonsai.

1 p.m.: Spring Garden Walk: Bonsai Collection Highlights During the scheduled Spring Garden Walk, I’ll be showcasing selections from the Garden’s Bonsai Collection and pointing out special spring highlights. (Note: due to the recent warm weather, the Korean lilac, wisteria, crabapple, or azalea bonsai may be in bloom.)

1 to 4 p.m.: Demonstration: Bonsai Landscape Planting I will demonstrate how I create a “landscape planting” with multiple bonsai on a rock slab.

I am happy to announce the addition of four bonsai trees on display in the Semitropical Greenhouse in the Regenstein Center.

Bonsai on display in the Semitropical Greenhouse

The crape myrtle, two ficus species, and natal plum trees were placed on display on March 28. The display will be up through the end of May with a change of tree species the last week of April. It’s the first time these trees are being displayed in this fashion here at the Garden, giving visitors the opportunity to see tropical and subtropical trees that otherwise would not be able to be shown in our courtyards until late May, due to temperature requirements.

The courtyards will open on Tuesday April 21, 2015, with our cold-hardy evergreen and deciduous trees.

This crape myrtle (Lagerstroemia) is continuing to respond very favorably to the root work we did.

This crape myrtle (Lagerstroemia) was the focus of my previous post on repotting. It is continuing to respond very favorably to the root work we did.

Crape myrtles are a genus of about fifty species of trees and shrubs native to South Asia, Northern Australia, and some Pacific islands. Some varieties can grow as tall as 100 feet, but most species grow as either small trees or large shrubs. Some varieties are deciduous, and some are broadleaf evergreens—this is a deciduous variety.

Crape myrtles are most famous for their flowers, which grow as clusters of small blooms. Flowering typically takes place between June and August. This tree has never flowered while here at the Garden. I am hoping that with the addition of a more appropriate soil mix, fertilizer changes, and a longer growing season we can can encourage this tree to bloom in the years to come.

The natal plum (Carissa grandiflora) is a dense evergreen tree with sharp spines. It’s native to tropical and subtropical regions of Africa, Australia, and Asia.

Our natal plum in fruit and flower at the same time!

Our natal plum produces beautiful flowers throughout the year. These can occur either as individual blooms or in clusters. The flowers have a powerful fragrance reminiscent of gardenia. The fruit is plum-shaped and can be red to dark purple-black in color. The fruit of the natal plum is edible and tastes like a giant cranberry—but please don’t eat ours! :)

Willow-leaf fig (Ficus salicifolia)

Chinese banyan (Ficus microcarpa)

Our two ficus trees on display are monsters! The Nabari (base of the tree) on these trees are huge, and they have a great presence. Ficus are tropical and subtropical trees native to southern Asia and India. However, they are also commonly found in South American countries and the southern United States. There are hundreds of species in the ficus genus in the world, but there are only about a half dozen that are commonly used for bonsai. Ficus benjamina, Ficus microcarpa, Ficus retusa (or Green Island fig), and Ficus salicifolia are among the most frequently used. These are great examples of tropical bonsai that will love their new temporary home in the Greenhouse.

Be sure to come down and see these amazing trees while they are on display! And keep a lookout for the new additions coming later this month. Here is a sneak peek at one of the trees you might see…can you tell what species it is?

This mystery tree might be blooming soon in the Regenstein Center—can you guess what it is?

Thanks for reading, and be sure to follow me on instagram @Windy_City_Bonsai for updates and pictures of the collection!

For many bonsai tree species, early spring is the best time for repotting.

As the days get longer and the temperatures slowly increase, the roots of a bonsai gradually become active. During this time, the energy of the tree that was stored in the roots over the winter begins to move back up into the tree branches. As this happens, the dormant buds begin to swell. This swelling is the first sign that the tree is beginning to break dormancy. Over the next few weeks, the amount of energy from the roots to the branches increases, and the buds go through a transformation from dormant nub to a fully-opened leaf.

Dormant bud

Swelling bud

Extending bud

Opening bud

The best time to repot is generally in the middle of this process, when the roots are active, and the buds are in the swelling and extending stage. All repotting should be done by the time the trees are in the opening stage.

The tree set to be repotted today is this wonderful crape myrtle (Lagerstroemia indica). The first step is removing the tree from the pot.

Crape myrtle (Lagerstroemia indica)

Using the root hook and saw, we slowly and carefully create a gap between the root ball and the sides of the pot. Creating this space will allow us to safely remove the tree from the pot.

Use the root hook to carefully loosen the plant from the pot.

Once a furrow has been created with the root hook, use the saw to free the bonsai from the pot.

This tree was certainly in need of being repotted! You can see the abundance of roots on the sides and the bottom of the root ball (below). You can even see where the roots started to grow down through the drainage holes in the pot. These “root plugs” prevent proper drainage, which is very important for tree health.

Root plugs—where the roots started to grow down through the drainage holes in the pot—prevent proper drainage.

Drainage screen covered by root mat

The frequency of repotting is determined by a number of factors, including species, stage of development, and pot size. Vigorous root growers like maples need to be repotted and root pruned more frequently than pine trees of the same developmental stage (which grow roots more slowly). Though root pruning is important to bonsai health, it can be stressful to a tree if the roots are disturbed too frequently. Knowing the tree species you have and how it grows is important in making the decision of when to repot and root prune.

Volunteer Ester Bannier assists in root trimming.

Use a root hook to work roots free.

Using root hooks, scissors, and chopsticks, the roots are teased out and pruned as needed. Cutting the roots back removes large woody roots, allowing more space for fine feeder roots to grow. The woody roots act only as transporters of energy. Woody roots do not absorb water, food, or oxygen; only the fine feeder roots do that. Having primarily fine feeder roots in our pots is what allows us to keep bonsai in such shallow containers. If the woody roots take up too much space, then the tree cannot absorb enough water, food, and oxygen to support the large amounts of foliage they have, and the trees’ health will suffer.

The bonsai, pre-trimming

The bonsai root ball after pruning

While the tree work is going on, the soil and pot are being prepared for its return.

Bonsai soil is one of the most important aspects of growing bonsai trees. There are many different soil mixes and combinations that can be used based upon your tree species, the region in which you live, the amount of time you have to water, and many other factors. No matter what mix you choose, a good bonsai soil should support vigorous root growth, a healthy microbe balance, and have good drainage. Here at the Chicago Botanic Garden, we use a variety of mixes based on tree species and stage of development. For this tree, we will be using our base mix of akadama (a clay-like material mined in Japan), pumice, and lava rock. Our soil mix is sifted to remove any small particles and dust that could clog up the drainage holes, decreasing drainage.

Once the pot has been cleaned, screens have been secured over drainage holes, and tie-down wires have been added, a layer of lava rock is placed to aid with drainage. After the drainage layer is placed, a small amount of soil is added to bring the tree up to grade and help position it in place.

Fresh mesh and tie-downs have been placed over drainage holes in the pot.

Drainage has been added in a single layer.

Once the tree is in place and secured, soil is added and chopsticks are used to push the soil into all the open spaces in and around the root system. Any open gaps left in the pot will result in dead space where roots will not grow. The soil should be firmly in place but not packed too tightly; otherwise, the drainage will be affected, and it will be difficult for roots to grow.

Adding soil to repotted bonsai

Chopsticks are used to push soil into open spaces around roots.

When the soil is set, the tree is soaked in a tub of water and a liquid product called K-L-N, which promotes root growth and reduces stress from the repotting process.

After a good soaking, the tree is removed and allowed to drain, then returned to its bench in the greenhouse. It will remain there until it is warm enough to go outside on the benches. Not all trees are moved to the greenhouse after repotting; most will return to the over-wintering storage. However, this tree was stressed at the end of the growing season, and I wanted to give it a jump-start on the year and give it more time to recover and gain back some of its vigor.

Soaking the repotted bonsai in water and K-L-N

Bonsai “benched” in the greenhouse until spring

In just a couple of weeks, the tree is fully leafed out, and has had a slight pruning to help balance the new growth throughout all the branches.

This tree is just the beginning of a busy repotting season here at the Bonsai Collection. We will most likely be repotting nearly 100 trees this year—nearly half the collection! Thanks for reading, and be sure to look out for more bonsai blogs to come in the months ahead.

A leafed-out bonsai, ready to display for the season

Upcoming bonsai events:

Tropical bonsai are installed in the Subtropical Greenhouse: Tuesday, March 31.

Trees return to the Regenstein Center’s two courtyards for the season: Tuesday, April 22.

Join us May 9 for World Bonsai Day demonstrations, and a tour of the courtyards.

Thirteen years ago, when I was working as an exotic animal veterinary technician, I bought my friend a gift—a juniper bonsai—that would set me on a course that I never could have imagined.

I already had a yard full of tropical plants, succulents, and orchids, but once I added my first bonsai, I knew something had changed. It was the beginning of a journey that took me from Gainesville, Florida, to Washington, D.C., to Japan and finally here to the Chicago Botanic Garden, where I am the curator in charge of the Bonsai Collection, which is known as one of the best of its kind in the world.

Tending this large bonsai is a delicate task.

Shortly after I purchased my first tree, I started learning about bonsai and joined a prominent bonsai club in Gainesville. In 2006, Gainesville (home of the Gators) hosted the State Bonsai Convention. That weekend was an eye-opening experience for me, as I got to learn from and assist international bonsai artists like Jim Smith, Colin Lewis, and others. That weekend convention was very influential and would fuel my desire to continue learning.

Less than a year after that convention, I had an opportunity to move to Baltimore, Maryland, and work at the National Aquarium. I quickly joined the Baltimore Bonsai Society and continued learning. Feeling more and more drawn to a career in horticulture, I made the move from veterinary technician to horticulturist of the Rainforest Exhibit at the National Aquarium. This opportunity made me think that I actually could have a career working with bonsai. Then, during a Baltimore Bonsai Club event at the National Arboretum’s Bonsai and Penjing Museum in Washington, D.C., I had a chance meeting with the curator Jack Sustic. I introduced myself by saying, “Hi, I’m Chris Baker. I have aspirations of being a bonsai curator some day, and I would like to volunteer here at the collection.” That sentence would forever alter my path. My time as a volunteer and then intern at the National Arboretum was inspirational and educational, and ultimately would lead me to Japan.

Jack Sustic would become a mentor and friend; he introduced me to Torhu Suzuki at the Daijuen Bonsai Nursery in Okazaki, Japan, where he had spent some time. Suzuki, or “Oyakata” (an honorific reserved for a person of high authority) as we would call him, was a third-generation bonsai master and prominent figure in Japanese bonsai culture. In 2012, I spent six months as an apprentice at Daijuen. In that time I learned so many lessons and skills that I use every day. It also gave me an entirely different perspective on how the practice of bonsai has evolved in Japan for centuries.

In April 2014, I started as the curator of bonsai at the Chicago Botanic Garden. Having the opportunity to be the first full-time curator here at a collection of this caliber is a dream job, which comes with a lot of expectations and responsibility. During the display season (April to November), horticulturists Joe Olsen and Gabe Hutchinson provided great support in keeping the trees watered and benches looking great for our visitors. The remaining trees are kept on the south end of the Garden, in the production area. Brian Clark, manager of plant production, and his team help care for the trees on my days off. Last but not least, the support of my 12 volunteers is essential. They are a great team of dedicated people who each brings something different to the Collection.

Volunteer Eileen Michal working on the Collection with me.

I’m often asked what has drawn me to bonsai, and why would I pursue a career in it, with only ten or so full-time curator jobs in the entire country? For me, bonsai starts with an appreciation of nature over all things. An ancient tree has the power to move people and evoke emotion. It’s what inspired the Chinese centuries ago to take something of beauty they saw in nature and grow it in a container.

Creating bonsai takes the eye of an artist, the horticultural knowledge of a botanist, and the hands of a mechanic. I have been painting and creating art with many mediums for years. I often draw my trees prior to styling them. It allows me to see different style ideas before I even touch a single branch. I love the horticultural aspect of bonsai, from soil science, to fertilizing, to advanced techniques of grafting and air layering. To me, the mechanical aspect is fun as well. I enjoy making large bends in branches using rebar and guy wires on developmental trees, as well as doing the fine detail work for a show-quality tree. A bonsai is never finished, and the skills and knowledge of a true bonsai expert take a lifetime of study to master and fully understand all it has to offer.

Bonsai has taught me many things, introduced me to wonderful people, and taken me to places I never thought I’d see…At this point in my life, it just seems silly for me to do anything else.